Air conditioning



July 17, 1956 J. w. Remmen 2,755,072

AIR CONDITIONING Filed July 12. 1954 2 Sheets-Sheet 2 STEAM HEATER (WMP/55.50@

8 esce/ven 4 /02 lNvEN-roR Joseph W Kreuner BY v www J ATTORN United States Patent O AIR CONDITIONING Joseph W. Kreuttner, North Tarrytown, N. Y. Application July 12, 1954, Serial No. 442,490

11 Claims. (Cl. 257-8) This invention relates to air conditioning, and more in particular to dual duct air conditioning systems and units.

An object of this invention .is to provide air conditioning systems and units which maintain desired temperatures and humidities throughout wide ranges of operating conditions. A further object is to provide such systems and units which will operate automatically throughout the year, i. e., for summer or hot outside temperatures, winter or cold outside temperatures, and intermediate temperatures. A further object is to provide systems and units of the above character which are adaptable to efiicient heat pump operations. part obvious, and in part pointed out below.

In the drawings:

Figure 1 is a schematic representation of one embodiment of the invention, and

Figures 2 and 3 are schematic representations of two other embodiments of the invention.

Referring to Figure 1 of the drawings, an air conditioning system is represented schematically as having a refrigeration system comprising a compressor 2, a first condenser 4, a second condenser 6, a receiver 8, and an evaporator 10, and there are standard controls. An air conduit system is also represented, where fresh air is drawn into the system at 12, and is directed by a damper 14 either to a chamber 16 and through a lilter 18 and condenser 6, or to a chamber and through a filter 22 and evaporator 10. Air from the conditioned space is returned through a conduit 24, and is directed by damper 14- to either of chambers 16 or 20 which is not then receiving fresh air. That is, with damper 14 positioned as shown in full lines, the fresh air ows to chamber 16 and the return air ows to chamber 20; when damper 14 is positioned as shown in broken lines, the fresh air flows to chamber 20 and the return air ows to chamber 16.

Air which flows through condenser 6 passes to a warm air plenum chamber 26, and is directed by a warm air fan 28 through condiut 30 to a damper 32. When damper 32 is positioned as shown, it directs the warm air to the outside through a condiut 34, but when the damper is swung to the broken line position, it directs the warm air through condenser 4 to a warm air duct 36. The air which lows through evaporator 10 passes to a cold air plenum chamber 38, from which it is directed by a fan through a cold-air duct 42. Duct 42 has a branch con-duit 44 extending to damper 32, so that cold air from duct 42 may be directed to the outside through conduit 34, when the damper is in the broken line position; or through the condenser 4 to the warm-air duct 36, when the damper iS positioned as shown. A supplementary heating coil is positioned in the path of the air flowing from condenser 4 to the warm-air duct 36. Hence, the air may be supplied with additional heating when desired.

. Duets 36 and 42 supply through a condiut to each zone or area of the conditioned space a fixed amount of warm or cold air or a mixture of the two streams which is necessary to maintain the desired conditions. Two of these air conduits are represented at 46 and 48, although it ,Y 2,755,072 Patented July 17, 1956 ICC , the refrigeration system operating, the air conditioning These and other objects will be in f system operates primarily for cooling the air in the conditioned zones. Hence, air returned from the conditioned zones or spaces flows to chamber 20, and thence through evaporator 10 to chamber 38, and through the fan 40 to the cold-air duct 42. A portion of this air, determined by the position of dampers 47 and 49, is diverted through conduit 44 and condenser 4 where .it is heated and thence to the warm-air duct 36, but the main portion of the air flows through duct 42 to the conditioned space through conduits 46 and 48. The fresh air which enters at 12 fiows through chamber 16, lter 18 and condenser 6 Where it absorbs the main portion of the heat of the refrigeration system, and thence to the warm-air plenum chamber 26. This air is directed by fan 28 through conduit 30 to damper 32 which is positioned to discharge the entire stream of air to the outside.

VThe cold air which is directed by fan 40 into duct 42 has low dew point and is cooled to an acceptable temperature. Hence, all of the air which flows to the conditioned space, including the portion which is reheated, has the desired dew point, and it is possible to maintain acceptable humidity conditions within the various zones of the conditioned space.

For winter operation, that is, when the conditioned zones require heating primarily, the dampers 14'and 32 are swung to their respective broken line positions so that the fresh air flows along the cooling path through evaporator 10, and cold air is supplied to duct 42, but the major portion is discharged to the outside at 34. At this time the return air flows along the heating path through condenser 6 and thence through condenser 4 and through the auxiliary heating coil 50 to the warm air duct 36. The cold air is still available in duct 42, but it is assumed that the major load is a demand for heating and therefore a relatively :small amount of the cold air is delivered to the conditioned zones. However, it should be noted that even with this mode of operation'all of the fresh air which passes into the conditioned space ows through the evaporator 10 so that excessive humidities can be avoided.

In this embodiment of the invention the dampers are moved manually, as discussed above, to change the system for summer or winter operation. However, the invention contemplates that the moving of these dampers may be automatic, and for this purpose thermostatic controls are provided which are responsive to the outside temperature and humidity conditions and which may be made responsive to inside conditions. The switchover from summer to winter operation can be at a relatively low outside temperature because the reheat feature in the air stream flowing to duct 36 will give substantial heating to zones which require heating while other zones require cooling. Furthermore, when certain Zones require a substantial amount of heating for a short period, steam or other heating medium may be supplied to coil 50 to supplement the heating action of the condenser 4.

In the embodiment of Figure 2 the construction and operation is somewhat similar to that of Figure 1. Hence, the system includes a refrigeration system as in Figure 1 ,with the elements being numbered correspondingly. VThe air circulating system includes a fresh air inlet 62, a return air conduit 6,4, a cold air fan 66, a warm air fan 68, and a damper 70 which is adapted to direct the fresh air upwardly through a filter 72 to the cold air fan or downwardly through a filter 74 to the warm air fan. As in the embodiment of Figure l, these two streams of air are directed oppositely when damper 70 is in the broken line position. Cold air fan 66 directs its stream of air through the evaporator coil into the cold air duct 76 and the warm air fan directs its stream of air through the condenser 6 into the warm air duct 78. However, in this embodiment the two ducts 76 and 78 are connected at their extreme ends through a duct 80 in which the condenser 4 is positioned.

The cold air duct 76 has an air outlet connection 82 which is closed when the damper 84 is in the full line position, and which may be opened by swinging this damper to the broken line position. When damper 84 is in the full line position, duct 76 is connected to duct 80. A hot air discharge conduit 86 is also provided which may be closed by swinging a damper 88 to its broken line position. However, when this damper is in the full line position the warm air is shut offr from duct 78 and is directed to the outside.

In Figure 2 the system is represented as operating with a major cooling load and with a minor heating load at times in certain of the zones. Hence, damper 84 is positioned to close off the cold air outlet 82 and damper 88 is positioned to discharge the warm air, and no steam is delivered to the heating coil 50. Damper 70 is positioned to direct the return air to the cold air fan 66 and then through evaporator 10 to the cold air duct 76. The major portion of the air is directed through the cold air supply dampers 49 to the various zones. However, for any heat ing load in any of the zones the warm air damper 47 opens, and this permits air to flow from duct 76 through duct 80 where the air is heated by condenser 4, and thence through the warm air duct 78 to the warm air damper and to the conditioned zone. Therefore, the operation is somewhat similar to that in Figure 1 except that the air to handle the heating load is taken from the end of the cold air duct to the warm air duct. For summer operation, the fresh air drawn in at 62 is directed by fan 68 to the condenser 6 and is discharged at 86.

When the system of Figure 2 is to be operated with the major load being heating, dampers 70, 84 and 88 are moved to their respective broken line positions. Hence, the return air flows through fan 68 and the condenser 6 to the warm air conduit 78 and additional heating may be provided by supplying steam to the coil 50. The fresh air ows through the cold air fan 66 and the evaporator 10 and it is discharged at 82. However, any cooling that is required is provided by air from the cold air duct 76 as discussed above.

In the embodiment of Figure 3, the refrigeration system has an evaporator 90 positioned above a condenser 92, and there is a perforated damper 94 positioned in an air inlet chamber between this evaporator and condenser. The return air is drawn by a fan 98 and the fresh air is drawn in through a filter 101 by a fan 100. The general arrangement of the conduits and the other elements of a refrigeration system are the same as in Figure l. With the air inlet damper 94 and with the air discharge damper 32 positioned as shown, the system is adapted for summer operation, i. e., for handling loads which are primarily that of cooling. Hence, the return air is directed by damper 94 upwardly through evaporator 90 to the cold air duct 42, and a portion of the stream is reheated by condenser 4 and flows through the warm air duct 36. The fresh air is directed from fan 100 downwardly through condenser 92 and flows through the duct 102 to damper 32 where it is discharged to the outside at 34. For operation when the major load is that of heating, dampers 94 and 32 are moved to their broken line positions so that the fresh air is blown through evaporator 90 and is discharged at 34. The return air then ows through condenser 92 and thence through conduit 102 to 4 condenser 4 and the heating coil 50 to the warm air duct 36.

As indicated above, damper 94 is perforated and the perforations are in the form of small openings of a maximum size of one-eighth of an inch. During the cooling operation the condensate from evaporator falls down onto damper 94 and passes through the perforations and drips onto the condenser 92. The condensate is reevaporated on the condenser and passes from the system with the warm stream of air. The perforations in damper 94 are not of sucient size to permit any substantial ow of air through them and yet they are of suicient size to pass the condensate under normal conditions of summer operation. Pressure on cold air side is normally higher than pressure on warm air side. Therefore, this differential aids the passage of condensate through small openings. The condensate thus is eliminated and in addition tends to reduce the temperature of air by adiabatic evaporation and thereby reduce condensing temperature.

During the summer operation, that is, when the major load is that of cooling, fan 98 directs the cold air stream through the evaporator 90 and thence through the two distribution ducts 36 and 42 to the conditioned zones. However, at that time fan merely draws in fresh air and discharges the air after it passes through the condenser 92 and conduit 102. Therefore, the load on the fan 98 and the head pressure built up by it above damper 94 is substantially greater than the head pressure of fan 100 beneath this damper. This difference in the head pressures insures that the condensate will flow through the perforations in the damper. During the winter operation when the major load is that of heating, fan 98 still operates to distribute the air through the system, whereas fan 100 is operating to merely pass the stream of fresh air through evaporator 90 and through the outlet 34. Therefore, the head pressure below damper 94 is higher than above it. However, during this time there is minimum condensation of moisture and therefore it is immaterial if the condensate does not pass through the perforations in the damper.

With each of the illustrative embodiments, it is assumed that the two fans are the same size and that they are centrifugal fans. The volume of air supplied by a constant speed centrifugal fan varies with the resistance against which the fan operates. Therefore, with either winter or summer operation the fan which is supplying air to the conditioned space has a greater resistance to ow than the other fan.

In each of the embodiments, one of the fans is operating at all times against low resistance so that it draws in a large quantity of fresh air and discharges this air mmediately, whereas the other fan is operating to direct a smaller quantity of air against substantial resistance because it must withdraw the air from the conditioned space and pass the air through the system back to the conditioned space. During summer operations, the cold air fan passes approximately one-half the volume that the warm air fan passes, and this insures a relatively high rate of heat transfer from the condenser to the larger volume of air even at high ambient temperatures. During winter operation the high rate of air ow is over the evaporator so that there is a relatively high rate of heat transfer from the air to the refrigerant. The systems constituting the illustrative embodiments of the present invention are adapted for various sized installations, for example, homes, office buildings and factories, and the system has special advantages where it is necessary to insure extremely close tolerances of temperature and humidity conditions.

I claim:

l. In an air conditioning system for a conditioned space having various zones, the combination of, a dual duct air distribution system comprising a warm air duct and a cold air duct which are adapted to make available supplies of warm air and cold air to the various zones of the condiakamoa tioned space, air flow control means to regulate the ow of air from each duct to each zone, whereby the desired temperature and humidity conditions may be maintained in the various zones of the conditioned space, a refrigeration system having a first condenser which is positioned to heat air moving to said warm air duct and a second condenser which is positioned to dissipate heat to a stream of air, said refrigeration system also including an evaporator which is adapted to cool a stream of air passing to said cold air duct, said refrigeration system also including a compressor and refrigerant lines forming a refrigerant circuit extending from said evaporator to said compressor and from said compressor through said rst and second condensers, a first fan causing air to flow through said second condenser, a second fan to cause air to ow through said evaporator, and air flow means including damper means and conduit means to direct a return air stream from the conditioned space either through said evaporator and thence to said cold air duct with a portion of the air entering said warm air duct through said first condenser, or to direct the return air stream through said first and second condensers to said warm air duct, said damper means being adapted to direct a stream of outside air either through said rst and second condensers and to the outside or through said evaporator to said cold air duct with flow of a portion thereof to the outside.

2. ln an air conditioning system, the combination of: an air circulating system comprising a pair of fans, one of which is adapted to direct a stream of air along a cooling path to a cold air duct and the other of which is adapted to direct a stream of air along a heating path to a hot air duct thereby to produce a stream of heated air, means to direct said heated stream of air alternately to the outside or tosaid hot air duct, means to direct a return stream or" air from the conditioned space along said cooling path and a stream of fresh air along said heating path or in the alternative to direct the return stream of air along said heating path and the stream of fresh air along said cooling path, means to direct a portion of the stream of cold air to said warm air duct or in the alternative to the outside; and a refrigeration system comprising, a compressor, a pair of condensers, an evaporator, and circuit means forming a closed series circuit through said condensers, evaporator and compressor, one of said condensers being positioned to heat the air owing to said warm air duct and the other being positioned to heat the air flowing along said heating path, and said evaporato being positioned to cool the air flowing along said cooling path.

3. In an air conditioning system, the combination of: a refrigeration system including, a compressor, a pair of condensers, one of which is adapted to re-heat air and thc other of which is adapted to heat air flowing along a heating path, an evaporator to cool air flowing along a cooling path; a pair of fan and duct assemblies positioned respectively to deliver air along said cooling and heating paths; a pair of parallel ducts adapted to carry respective streams of cold and warm air which pass along said cooling and heating paths; a re-heating duct means connecting the remote'ends of said parallel ducts and containing said reheating condenser whereby air may ow from said cold air path direct through said re-heating coil to said warm air duct; air discharge means to discharge the air to the outside after it has passed along said heating path or in the alternative to discharge to the outside a portion of the air which is passed along said cooling path; and means to supply a stream of return air from the conditioned space to said cooling path and a stream of fresh air to said heating path, or in the alternative to supply a stream of return air to said heating path and a stream of fresh air to said cooling path.

4. In an air conditioning system, the combination of, a dual duct air circulating system including a cold air duct to carry a stream of cold air to the conditioned space and a warm air duct to carry a stream of warm air to 6 the conditioned space, a refrigeration system which is adapted to condition streams of air passing to said ducts and including a first condenser positioned at the entrance of said warm air duct and a second condenser positioned along an air heating path, said refrigeration systern also including an evaporator positioned along an air cooling path and a compressor which is adapted to circulate refrigerant from said evaporator through said lirst and second condensers, separate fan means to direct separate streams of air respectively along said heating path and said cooling path, and damper means to pass the air from said heating path to the outside and to pass a portion of the air from said cooling path to said cold air duct and the other portion through said first condenser to said warm air duct or in the alternative to pass the air from said heating path through said rst condenser to said warm air duct and pass a portion of the air from said cooling path to the outside.

5. A system as described in claim 4 which includes, a return air duct to carry air from the conditioned space alternatively to said cooling or heating paths, and means to supply fresh air in the alternative to said heating or cooling paths.

6. The air conditioning system as described in claim 4 wherein said evaporator is positioned directly over said second condenser and which includes, a damper adapted to divert one stream of air upwardly through said evaporator and the other stream of air downwardly through said second condenser, said damper comprising a perforated plate which is adapted to pass condensate from said evaporator to said second condenser.

7. The air conditioning system as described in claim 4 which includes, an auxiliary heating coil positioned in the path of air flowing from said rst condenser to said warm air duct.

8. In an air conditioning system, the combination of: a refrigeration system comprising, a compressor, a rst condenser which is connected to receive compressed refrigerant from said compressor, a second condenser which is adapted to receive refrigerant from said first condenser, an evaporator which is adapted to receive liquid refrigerant from said second condenser and which is connected to said compressor; a warm air circulating system which is adapted to receive a first stream of air and to direct the air through said second condenser and thence alternatively to the outside or to the conditioned space; and a cold air circulating system which is adapted to receive a second stream of air and to direct the air through said evaporator and thence to supply the desired portion of the cold air to the conditioned space and to pass the remainder of the cold air through said first condenser thereby to reheat the air to the conditioned space, said cold air circulating system including means to direct a portion of the cold air to the outside.

9. An air conditioning system as described in claim 8 which includes, means positioning said evaporator directly over one of said condensers with an air entry passageway therebetween, and wherein said air circulating systems include a damper which is adapted to direct said first and second streams of air respectively upwardly through said evaporator and downwardly through said condenser, said damper having openings therethrough for the passage of condensate from said evaporator.

10. A system as described in claim 9 wherein said damper is in the form of a perforated plate having perforations not greater than the order of one-eighth of an inch in diameter, and wherein said air circulating systems include fans directing said streams of air toward the space occupied by said damper whereby air pressure conditions are created on the two sides of said damper.

1l. An air conditioning system as described in claim 8 wherein said air circulating systems include a dual duct system through which the cold air stream and the warm 7 8 air stream ow respectively, a connecting duct between References Cited in the file of this patent said dtlcts it; wh ich .said r st condenser is positiorted, and UNITED STATES PATENTS whereln sald alr clrculatmg systems Include dlscharge 2 376 859 B dampers which provide for the discharge of the air from eau May 29' 1945 the air streams. 5 2,468,626 Graham Apr. 26, 1949 

